Electrical stimulators may be external or implanted, and may be used to deliver electrical stimulation therapy to patients to various nerve and/or tissue sites to treat a variety of symptoms or conditions such as chronic pain, tremor, Parkinson's disease, epilepsy, urinary or fecal incontinence, sexual dysfunction, obesity, or gastroparesis. In general, an implantable stimulator delivers neurostimulation therapy in the form of electrical pulses, although other continuous waveforms may also be used. An implantable stimulator may deliver neurostimulation therapy via one or more leads that include electrodes located proximate to target locations associated with the brain, the spinal cord, pelvic nerves, peripheral nerves, or the gastrointestinal tract of a patient. Hence, stimulation may be used in different therapeutic applications, such as deep brain stimulation (DBS), spinal cord stimulation (SCS), pelvic stimulation, gastric stimulation, or peripheral nerve field stimulation (PNFS).
In general, a clinician may select values for a number of programmable parameters in order to define the electrical stimulation therapy to be delivered by the implantable stimulator to a patient. For example, the clinician ordinarily selects one or more electrodes, a polarity of each selected electrode, a voltage or current amplitude, a pulse width, and a pulse frequency as stimulation parameters. A set of parameters, such as a set including electrode combination, electrode polarity, amplitude, pulse width and pulse rate, may be referred to as a program in the sense that they define the electrical stimulation therapy to be delivered to the patient. The clinician may create one or more programs that each includes a selected set of these stimulation parameters. As the patient receives therapy over time, the patient may select, or the system may automatically select, different programs to change the electrical stimulation. Each program may be directed to treat a different anatomical region of the patient, provide an alternative therapy, address a different symptom, or otherwise adjust the stimulation therapy.